A conventionally known technology disclosed, for instance, in JP-2006-046140-A suppresses the occurrence of an abnormal combustion in a situation where an abnormal combustion, such as pre-ignition (a phenomenon in which combustion is initiated earlier than ignition timing to generate an excessive in-cylinder pressure), might occur in a combustion chamber of an internal combustion engine. When a precursor of pre-ignition is detected, the technology disclosed in JP-2006-046140-A exercises control to suppress the occurrence of pre-ignition by increasing the amount of fuel or retarding the ignition timing.
The applicant of the present invention has acknowledged that the following documents relate to the present invention including the aforementioned document.